Valve's monthly hardware survey is a snapshot of what all those tens of millions of users have installed on their gaming PCs. The latest numbers from December 2013 show the use of Windows 8 or 8.1 on Steam reached a new milestone. 20.06 percent of all users who volunteered to send their hardware information have either Windows 8 or 8.1 installed on their rigs.

Specifically, the survey shows that Windows 8 is installed on 11.22 percent of PCs that connect to Steam, while Windows 8.1 was found on 8.84 percent of those computers (both numbers combine the 32-bit and 64-bit SKUs). The updated stats mean that just over one in five PCs that sign up to use Steam do so with Windows 8 or 8.1.

Windows 7 claims the top spot as the most used OS on Steam. In December, its share of users was 62.96 percent, compared to 64.38 percent in November.